there are a lot of ways you could define “free software”. for example, you could say candy crush or CCleaner is free software, because you can install it for free.
when people say that software is “free as in freedom”, or “libre”, they mean something else. under these definitions, neither candy crush nor CCleaner would be free software. in order to be free by these definitions, software needs to fulfil these four criteria
- the ability to run the software for any reason, without restrictions. this means that the free version of teamviewer is not libre, as it tells you that you must purchase a license to use it commercially.
- being able to study and modify the program’s inner workings. this requires the source code being available. software that doesn’t provide the source code thus cannot fulfil this term, and software like snapchat, which bans users for running modified versions, is definitely not one of these.
- being allowed to redistribute the software. if you buy a macbook, you can install updates for free, but you certainly aren’t allowed to redistribute these updates.
- being allowed to distribute modified versions to others. if you’re not allowed to download the app, make some changes, and send that to people, it breaks this rule. the youtube app is free, but google wouldn’t allow you to do this.
all of the software mentioned in those four basic rules is “free”, but not free. this distinction is often used by saying “gratis” or “libre” – gratis software is free as in “free donuts”, but libre software is free as in “freedom”.
as with anything, it’s hard to make clear cut rules to define what is and isn’t an example of libre software. the cooperative software license prohibits most companies from using the software, but is otherwise entirely libre. this violates the first rule above, but i would say it’s still a free software license, although the free software foundation would disagree with me on that.
and finally, here’s a link to the FSF’s article on what is and isn’t free software. this is where those four rules came from – the FSF calls them the four essential freedoms. https://www.gnu.org/philosophy/free-sw.en.html
neither of these links are necessarily an endorsement of the content contained within.